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How much slower would a cyclocross bike be on tarmac?

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  • August 3, 2016 at 8:34 pm #26095
    road

    Say I was after something with 32-35c tyres, weighs about 10kg as opposed to my current ride at 8.5, probably a bit more upright/relaxed in riding position. If I averaged about 18mph on the way to work, what would I average for the same effort on the cyclocross bike (thinking Giant Anyroad/Caadx 105)?

    I think I’ve probably just got one of those urges to buy something new but a guy at work turned up on a new Caadx and I liked it. 

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  • August 4, 2016 at 1:27 pm #876121
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    darnac

    I’ve got a Wilier Cross

    I’ve got a Wilier Cross-Carbon Di2 which I use as my Winter bike. It’s got 28 mm Conti 4 Seasons and a 50/34 chainring and 12-32 cassette. Weight 8.7 kgs with pedals. I go up the same climbs as on my other road bikes (I live in the Pyrenees) but as it’s about 1.5 kgs heavier I notice a difference – but I still get there!

    August 4, 2016 at 9:52 am #876119
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    Anonymous

    Thanks for the responses,

    Thanks for the responses, maybe the best compromise if I got one would be those tyres with a slicker centre and more knobbled edges? Or maybe just road specific tyres. 

    One of the reason I’m looking at this is the roads are getting so crap it’s giving me pins and needles in my hands. When I’m out and about on better roads it’s never a problem but only my commute roads. I’m guessing the constant vibration is giving me the problem?

    August 4, 2016 at 9:23 am #876117
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    Rod Marton

    Probably a few percent slower

    Probably a few percent slower, more if your route is hilly, less if the road surfaces are poor. But this assumes a reasonably smooth road/gravel tyre: knobblies will slow you down a lot more.

    I few years ago I tried swapping bikes around on the local club 10 mile TT: the audax bike was about 2.5% slower than the road bike and the MTB about 10% slower. A cross bike would be between the two: probably closer to the audax bike if you set it up with road tyres.

    August 4, 2016 at 9:19 am #876115
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    BrokenBootneck

    I have set most of my k.o.m’s

    I have set most of my k.o.m’s on my board man CX with either 32 or 28’s on (slick) a lot whilst carrying a rucksack. True I tend to ride these roads on my commute and not on a Sunday but have always felt that the bigger tyres absorbed the vibrations etc from the crappy road surfaces allowing me to go faster for longer rather than bouncing around feeling fast but not going fast on skinny tyres. But I have set the bike up aggressively for speed so the aero ish effect helps too. 

     

    Choice of tyre. Duranos heavy but bombproof 3 years thousands of miles not one puncture. 

    August 4, 2016 at 8:56 am #876113
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    tritecommentbot

    GCN’s Pimp My Commute episode

    GCN’s Pimp My Commute episode

     

     

    They were looking at aerodynamics and put their tester on their standard road bike and full on baggy commuter clothes to an aero bike with lycra kit.

     

    Standard road + commuter clothing: 58:32

    Aero bike + lycra: 52:12

     

    Psychology probably played a part there too.

    August 4, 2016 at 8:43 am #876111
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    BBB

    Knobs will increase rolling

    Knobs will increase rolling resistance but tyre design and compound still matter especially as over time the tread will be wearing down.

    E.g. 35mm Schwalbe G-One especially when run tubeless, would probably roll at least as fast as many popular commuting road tyres especially hosepipes like Gatorskins. The worse the road surface the bigger the advantage.

    Personally my choice for fast comuting would be a pair of Schwalbe 30mm S-Ones run tubeless. On wider rims they would stretch to about 32mm and you wouldn’t need to run them at more than 60-70PSI. Fast comfortable and with ultimate puncture protection.

    As for body position, there’s no reason why a cx / all road bike couldn’t be set up  like a regular road bike.

     

    August 4, 2016 at 6:37 am #876109
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    Jimthebikeguy.com

    Gearing might play a part. If
    Gearing might play a part. If its a 2x it may be that your quickest gear could be 46.11 – if its a 1x you could be as low as a 42×11 (or 10 for SRAM). If you are fairly powerful (18mph average commute sounds good) then you might find – on road tires at least – that you could overrun the gearing. On CX knobblies you probably wont though.

    August 4, 2016 at 6:03 am #876107
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    tritecommentbot

    Maybe round 10% slower. 

    Maybe round 10% slower. 

     

    What I did was look at my first road rides on my old Specialized Stumpjumper Evo HT 29er after a 4 year break (big knobbly Specialized Purgatory Control tyres). Average speed was 14mph.

     

    Then looked at my first rides on my carbon fibre road bike this year with Continental 25mm tyres (after a 5 year break from cycling). Average speed was 17.5mph.

     

    That’s a 20% difference. 

     

    Probably around 2kg weight difference between the two bikes (the mountain bike is actually pretty light which is why I listed the model, probably comparable to cyclocross bikes) so the main difference here are the tyres. 

     

    Cyclocross tyres are somewhere in between road and mountain bike so I just halved the 20%.

     

    Rough calc puts you at 16.2mph.

     

    A lot of these cyclocross bikes actually have more roadie looking fast tyres, so you could be looking at 17mph. The weight difference won’t be that noticeable. Less than .5mph.

    August 3, 2016 at 8:48 pm #876105
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    mattydubster

    Hi.  I have an Enigma Ecroix,

    Hi.  I have an Enigma Ecroix, which is basically a gravel/cross bike with massive tyre clearances.  What I’ve learned is that if you have knobbly tires at about 35c they tend to be noticably slower, and you can actually hear the drag noise when on the road – but I have normal 28c road tyres on mine most of the time and don’t really notice any difference, even with a huge headtube which keeps me as far away from a racing position as possible!  I have even been paying attention to the weight of late, and have managed to get the bike down to about 8.7kg. 

     

    CaadX seems like a lovely bike. 

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